# Smoking room heat - know anything about HRVs or PTACs?



## StogieNinja (Jul 29, 2009)

Anyone know anything about HRVs or PTACs? I've been trying to figure out a good heating and eventalation system for a smoking room. Both options have been presented. Anyone work with either kind of system or know of a similar solution? 

Basically I'm putting in an exhaust fan into a 10x12 room with 10ft ceilings, and need a way to make the fresh air coming into the room warm.


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## kapathy (Nov 20, 2010)

can you run a gas line? if so get this...buddy uses it in his garage in chicago winter and its 70 plus in his garage

Amazon.com: Mr. Heater VF 30K GARAGE LP ventfree wall mount: Home & Kitchen

or get the propane attchment if not... it will suck propane 11-12 hours on high for a 20 lb (bbq size) tank.....worth the money....silent and good heat... just mount a small* METAL* oscillating fan above it to move the air a little bit


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## Flapjack23 (Jan 18, 2012)

I put a HRV system in my house when I built it in 2007. Does a great job, but would be overkill for 1 room. Don't remember what size/model I had installed, but I have "vents" in 3 bathrooms, 1 in the kitchen, and 1 in the laundry room. If I remember correctly, it was a couple grand installed, but he was also the contractor who installed my furnace. When I finish my basement, I think I will expand the one I have or put a smaller unit for the basement itself. 

The HRV basically has exhausts air through a heat exchanger and dumps the "preheated" air into the cold air return on my furnace. I probably get half of the heat back when its running...if its 70F in my house and 30F outside, through the heat exchange process, stale air is vented, fresh air is taken in, goes through the heat exchanger where if becomes about 50F and dumps into the return on the furnace.

Better than make up air entering the system at ambient outside air temp.


EDIT: I'm guessing a different HRV?


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## StogieNinja (Jul 29, 2009)

kapathy said:


> can you run a gas line? if so get this...buddy uses it in his garage in chicago winter and its 70 plus in his garage
> 
> Amazon.com: Mr. Heater VF 30K GARAGE LP ventfree wall mount: Home & Kitchen
> 
> or get the propane attchment if not... it will suck propane 11-12 hours on high for a 20 lb (bbq size) tank.....worth the money....silent and good heat... just mount a small* METAL* oscillating fan above it to move the air a little bit


I might be able to run a gas line, actually. The gas line passes overhead just outside the entry door...

Does it heat efficiently enough to warm the room even as the overhead ventilation is sucking air out of the room?

My concern is that with the overhead ventilation sucking smoke/air out, cold air will becoming in through the air return, so the heater either needs to be able to over-power the cold coming in through the fresh air return, or else I need to heat the air as it comes in.


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## kapathy (Nov 20, 2010)

that should be way more than enough...especially with 10' cielings just play with it a little bit you shouldnt need to run the exhaust non stop so you can save some heat.


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## StogieNinja (Jul 29, 2009)

kapathy said:


> that should be way more than enough...especially with 10' cielings just play with it a little bit you shouldnt need to run the exhaust non stop so you can save some heat.


Thanks, Kevin... you're a gentleman _and _a scholar!

A stinky, barnyard, llama-scholar, but I digress...


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## Johnny Rock (Jun 25, 2010)

10 X 12 X 10 = 1200 cubic ft. If you exhaust 100 CFM you will exchange the air in the room every 12 minutes. Pretty comfortale. 

My solution would be a 6-8k btu thru the window/wall room A/C with heat (and fan only option) and a 100 cfm exhaust fan.

This gives you flexibility to regulate temps based on outdoor ambient. The A/C unit should draw enough air in from the outside for heat/A/C, fan only.


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## StogieNinja (Jul 29, 2009)

Johnny Rock said:


> 10 X 12 X 10 = 1200 cubic ft. If you exhaust 100 CFM you will exchange the air in the room every 12 minutes. Pretty comfortale.
> 
> My solution would be a 6-8k btu thru the window/wall room A/C with heat (and fan only option) and a 100 cfm exhaust fan.
> 
> This gives you flexibility to regulate temps based on outdoor ambient. The A/C unit draws air in from the outside for heat/A/C, fan only.


Interesting... so basically, I wouldn't need to add a fresh air intake at all, as the wall unit would be supplying the necessary air by pulling it from outside, and heating or cooling it as it comes in, yes?

Would something like this work:

http://www.portablehomeair.com/stor...all-Air-Conditioner-with-Heat_1097691404.html

It has up to 290 CFM airflow... so if I put in an exhaust fan that has say 300CFM, that will create negative airflow, which I presume I'd want for the smoking room, and the room stays comfy due to warm air entering instead of cold air... sounds perfect!


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## Johnny Rock (Jun 25, 2010)

Most decent units will allow a percentage of outside air to be mixed with the heat/ a/c, or fan.

On that unit if the energy saving mode allows outside air to be mixed, it should be cool...no pun, ok yes it was intended..

10k btu may be overkill though. 6-8k on 1200 cubic ft. is plenty, unless you want to to turn the entire room into a humidor @ 65 degrees.

BTW if you install any more than 100 cfm exhaust fan, I would look into an inline unit that mounts in the attic, otherwise it will be very noisy.


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## StogieNinja (Jul 29, 2009)

Johnny Rock said:


> Most decent units will allow a percentage of outside air to be mixed with the heat/ a/c, or fan.
> 
> On that unit if the energy saving mode allows outside air to be mixed, it should be cool...no pun, ok yes it was intended..
> 
> ...


The space directly over the smoking room is, in fact, attic space. I was thinking about an exterior-mounted fan, actually which should further lower the noise in the room.

The one question is, how much air will the through-the-wall unit bring in? Cause if I understand correctly, the ventillation fan won't really do a ton of good unless the air coming in is roughly equivalent to (or ideally just slightly less) than the air going out, right?

I really thought there would be a very simple way to put some kind of inline heater where the air comes in and heat it as it comes through and into the room.


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## Johnny Rock (Jun 25, 2010)

First question: When was your house built, and how old are the windows, and doors?

If your house was built prior to the late '80s early '90's, there will be sufficient enough infiltration through the windows and doors to provide a 100-150 cfm exhaust fan with dilution. Houses built before this time were not exactly air tight. If not, a simple 4" duct vented to the attic space (if the attic is ventilated) should provide enough make up air for the exhaust fan. Position the air intake from the make up air in the general area of the heat and you should be good. Don't oversize the exhaust or the fresh air for best results.


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## StogieNinja (Jul 29, 2009)

Johnny Rock said:


> First question: When was your house built, and how old are the windows, and doors?
> 
> If your house was built prior to the late '80s early '90's, there will be sufficient enough infiltration through the windows and doors to provide a 100-150 cfm exhaust fan with dilution. Houses built before this time were not exactly air tight. If not, a simple 4" duct vented to the attic space (if the attic is ventilated) should provide enough make up air for the exhaust fan. Position the air intake from the make up air in the general area of the heat and you should be good. Don't oversize the exhaust or the fresh air for best results.


House was built in 2001, I think. It's in the back part of an "L"- shaped 3-car garage. Attic space above. Two walls are exterior, one with a door to the back patio. The wall opposite the exterior door was just built, has a door, and faces the interior of the garage. The wall opposite the other exterior wall has our living room on the other side.

So I'm thinking a vent in the ceiling, running the duct into the attic, and then sideways to the exterior wall of the attic, with the fan mounted on the outside to pull air out of the room. Air intake would probably go low on the exterior wall somewhere.

The one question I have about the through-the-wall unit is that if it's pulling air from inside, heating it, and recirculating it, wont it be pulling smokey air though the unit, heating it, and then recirculating it, eventually causing the air going through to smell worse as the smoke residue collects inside? I'm unfamliliar with how all this works, so please pardon my lack of understanding!

Part of the reason I was looking at something like an in-line heater to heat the incoming air was so that the air being circulated was always fresh.

Kevin's idea is to just overpower the cold of the incoming fresh air with lots of radiant heat, it sounds like. Yours is to just not move all the air out of the room as quickly and basically let the air warm as it circulates, yes?

I think part of what I'm trying to figure out is that the room freezes with the door cracked open, but cracking the door isn't even clearning all the smoke out. But perhaps I'm letting all the heat out without really ventilating the room enough, whereas once the room is ventillated the heat won't escape as quickly? I dunno... :noidea:


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## Displaced (Jan 4, 2012)

I'd like to start off by asking a few questions:

By the time I posted this you already answered some of these questions:

What kind of space are you converting? Is it a patio, sun room, spare bed room? 
Is it well insulated?
What room is next to it? 
What spaces are above and below? Attic, basement, other room?
What kind of heating system? Hot water baseboard? Gas-fired forced Air?
What kind of cooling system? Forced Air AC? Window units?
How many people do you think will be in there at one time?


Assuming you have forced air and you're using a spare room that is not a closed in patio, my initial thoughts are:

I don't think 100CFM is enough exhaust. That is about 5 Air Changes an hour. I would suggest you go a minimum of 8-10 Air Changes. If you see having more than one person smoking at a time I may even recommend 12 air changes per hour. You can then wire in a speed controller to slow the fan for when it's just you and then increase it when your buddies are over.

10*12*10 = 1200 CF --> 
1200 CF * 8 Air Changes / 60 Minutes = 160 CFM
1200 CF *10 Air Changes / 60 Minutes = 200 CFM

If you install an exhaust fan for 160 CFM that would make your smoking room negative to your house by 160 CFM. Depending on how tight the building construction is, air will leak in to make up what you're exhausting which can be through, windows, doors, air ducts, etc. 

It sounds like you have forced air. I would suggest sealing closing off your returns and still have the supply air to the space. Without knowing what your floor plan looks like, and assuming you have swinging wood doors. I would suggest undercutting the door by 1 inch and let the air come from the next room. Your house infiltration will then make up for what you're exhausting which will then be conditioned by your furnace. 

Residential AC units aren't designed to bring in a whole lot of outside air. Most residential equipment will max out between 10-15% of outside air. So that 290 CFM window unit will theoretically allow you to bring in between 29 and 43 CFM of outside air. Assuming 160 CFM of exhaust, that's still a negative of 131 to 117 CFM. The difference will still need to be made up someplace. So I would still suggest the above. 

This all really depends on if I made the right assumptions.


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## Displaced (Jan 4, 2012)

Aninjaforallseasons said:


> Part of the reason I was looking at something like an in-line heater to heat the incoming air was so that the air being circulated was always fresh.
> 
> Kevin's idea is to just overpower the cold of the incoming fresh air with lots of radiant heat, it sounds like. Yours is to just not move all the air out of the room as quickly and basically let the air warm as it circulates, yes?
> 
> I think part of what I'm trying to figure out is that the room freezes with the door cracked open, but cracking the door isn't even clearning all the smoke out. But perhaps I'm letting all the heat out without really ventilating the room enough, whereas once the room is ventillated the heat won't escape as quickly? I dunno... :noidea:


If you want to bring in air directly from outside you will need to condition it to make it neutral temp. Assuming 160 CFM of 15 Deg outside air, and 70 deg space temp, BTU Heating = 1.08*160 CFM * (70 deg F - 15 Deg F)

You would need 9500 BTU of heat to turn 15 deg air into 70 deg air just so you feel comfortable.


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## Johnny Rock (Jun 25, 2010)

If you draw too much air out of the room, you will be taking the heat with it. If you balance the intake/exhaust air, then whatever heat you remove, you will need to re-supply.

If you provide a six inch make-up air duct into the space from the ventilated attic, configure it with a barometric (weighted damper). Then you can install a variable speed exhaust fan you can adjust based on the load. The damper will open and close based on the negative pressure in the room.

I still think a 6-8k btu a/c unit with heat is plenty for the size space you have.

BTW, don't count on there being to much free air (infiltration) in the rest of your house. Window and door mfg's. were required to comply with strict energy efficiency regulations for leakage starting in 1994, so your house should have minimal infiltration.


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## StogieNinja (Jul 29, 2009)

Thank you both for the information, this is all helpful and being filed somewhere in the recesses of my brain.


...which is to say I'll be coming back to this thread to re-read often!



Dante, there's no air at all currently being piped into the room, either in or out. So it will be an entirely new -and independent- ventilation system, both incoming and outgoing.The only air getting into the room (as far as I can tell) is in the slight crack under the rear exterior door leading out to the patio. We weatherstripped the interior door leading into the rest of the garage.

I think I want to go with up to a 400CFM fan, just based on the fact that there are often going to be 3-4 guys in there including myself on a regular basis, and up to 6 or 7 from time to time, and install a switch like you recommended. 

Dante, I life in the PacNW, so it's RARELY down to 30*, usually somewhere in the 40's even in the winter. So assuming a 30*temp, and a comfort level of 70, what BTU would I need? (Although it sounds like John is right, 6-8k is about right for that?)

John, is there a reason to run the pipe up to the attic for the air intake, as opposed to just running it directly through the wall to the outside of the house? 

THank you all for your help, I'll try to get a drawing of what the house looks like ASAP!


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## Johnny Rock (Jun 25, 2010)

Only because the air in your attic will be warmer than the outside air.


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## StogieNinja (Jul 29, 2009)

Ah.. good point... ok, so presuming I bring air down into the attic, no smoke goes back up into the attic as long as the fan is on... but what happens after the fan turns off? I'm worried about the smoke getting into the attic as it's got a lot of stuff in there I don't want to smell smokey.

Also, here's the image of the room:










Above the smoking room is a small attic space
Above the living room is our bedroom
Above the garage is the bonus/entertainment room, which has a half-door leading into the small attic space.

My original thought was a 400CFM exterior-mounted fan pulling air from the middle of the ceiling, running the duct up into the attic and then east to the exterior of the house.

Then put in a fresh-air intake low on the east wall in either the northeast or southeast corner, and somehow figure out how to warm that air coming in.

John, you mentioned that if there's a lot of circulation, it'll pull the heat out. That's why I assume I need to heat the fresh air coming into the room. If I put a fresh-air intake in the lower left corner of the east wall, could I just put a heater on the north wall real close to it and blast the air with heat as it enters the room?


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## Displaced (Jan 4, 2012)

You're correct about having to heat the outiside air coming in. BTU heating = 1.08*400 CFM*(70F-30F) = 17,280.

As a side note, the relationship between the amount of outside air you bring in VS the heating required is directly proportional. So if you install a speed controller on the fan to drop the exhaust to 200 CFM you would need half the heating. 

I assume your attic has vented soffit and a ridge vent. Most newer homes do, and if that's the case you might end up having a pretty cold attic.


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## StogieNinja (Jul 29, 2009)

Displaced said:


> You're correct about having to heat the outiside air coming in. BTU heating = 1.08*400 CFM*(70F-30F) = 17,280.
> 
> As a side note, the relationship between the amount of outside air you bring in VS the heating required is directly proportional. So if you install a speed controller on the fan to drop the exhaust to 200 CFM you would need half the heating.
> 
> I assume your attic has vented soffit and a ridge vent. Most newer homes do, and if that's the case you might end up having a pretty cold attic.


That's indeed the case. It's about the same as the outside, just without the windchill. All the insulation is against the interior walls of the bedroom and entertainment room, the attic is basically just board and roofing. So yeah, it's cold in winter.

That being the case, would it make more sense just to put in a little intake vent in the exterior east wall?

So, according to the formula above, if I'm heating 30* air to 70*, I need 18k BTU; if I'm heating 35* air to 65*, I'd need 13k BTU, yes?

I'd like something adjustable, as most of the time the temp is more like 45-55, so we only need to heat it say 10-15 degrees. It's only for about 2-3 months a year we need more heat.

Do they make any kind of adjustable heaters that can heat incoming fresh air? I thought I'd be able to just buy something that fit right in the intake that had heating coils or something that heated the air as it passed through into the room, but I can't seem to find anything remotely like that online.


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## Displaced (Jan 4, 2012)

This is going to be a short answer and I apologize. I can't reply while I'm at work and I'm only home for a few minutes then have to run out for the night. I'll get more elaborate tomorrow. 

Your math is good. You'll need about 13,000 btu (or 13MBH) to heat the air you want to replace. From your sketch it looks like your smoking room is an unconditioned space. Is that true? Are you planning on doing any heating just to keep it up to temp?


To heat the air I think you're going to need an electric duct heater. They make them for residential forced air systems. I didn't have a chance to really look at any today. If google them you'll see that they are rated in kW for heating. kw=BTU/3412

Almost all electric duct equipment are designed to raise the air temperature between 25-30 degrees. So that would be perfect for you. You may need a little extra heat in your space for those colder days.

I don't want to make this too complicated that you can't do it yourself. It's pretty simple stuff once you get past the fundamentals.

Oh, and i guess I should ask how comfortable you are at doing ductwork and electrical by yourself?


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## StogieNinja (Jul 29, 2009)

Dante, thank you for the reply! Sounds like I need 4 kw (13k BTU/3412 = 3.81). I'm going to google those electric duct heaters now, and see what I find, but 25-30 degrees sounds fine for most occasions.

Between me and my brother-in-law, the duct work should be a snap, and the electrical only slightly more complicated; he's a contractor, and rewired his entire house, so I'm guessing he's familiar enough to get the job done.



Displaced said:


> This is going to be a short answer and I apologize. I can't reply while I'm at work and I'm only home for a few minutes then have to run out for the night. I'll get more elaborate tomorrow.
> 
> Your math is good. You'll need about 13,000 btu (or 13MBH) to heat the air you want to replace. From your sketch it looks like your smoking room is an unconditioned space. Is that true? Are you planning on doing any heating just to keep it up to temp?
> 
> ...


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## Displaced (Jan 4, 2012)

I did some looking around and I found this electric duct heater.

Electro Industries EM-WX0515R Electric Duct Heater 5KW 8" Pipe Section 350CFM, 240V

They have a manual on using it to heat make up air. Which is what you need.

http://www.electromn.com/pdf/EL003.pdf

They also have an installation manual

http://www.electromn.com/pdf/manuals/EI904.pdf

I think the 350 CFM 5kW unit is what you're looking for. It has a remote sensor that you install down stream of the unit and it will sense when the air is too cold and needs to be heated. The manuals go through a simple setup so you can graphically see how it works.


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## StogieNinja (Jul 29, 2009)

Ouch. $550 hurts. But it does look exactly like what I need/want, I just had no idea it would be that expensive just for the heater. Then again, I'm learning _everything _costs more than I think it will!

One question: There are a ton of parts in that diagram there... do I really need a motorized damper, insulated connector, filter section, blower, and another insulated connector? Could I just cut a hole in the wall, cover it with a cent screen, run it right through the heater, and into the room?

Thanks again, Dante!


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## Displaced (Jan 4, 2012)

A wall cap with insect screen and a barometric damper so it opens when your bringing air in. everything else is for a normal installation and this isn't normal.

Do you think you'll just install it as a hard connection to the outside because if that's the case the other thing you can do is just install a wall cap with a damper on it and when your fan kicks on it would let the air come in and then you can use electric baseboard heat or something like that to heat your space. As long as you have enough capacity to heat the air it'll do the same thing but you might feel a draft. That's probably a simpler and easier way to do it. 

What i would recommend you do is start off with the just the exhaust fan setup and try just exhausting air. You might just have enough leakage to make up what your exhausting, but if you don't then you can add in the outside air connection and heaters.


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## Displaced (Jan 4, 2012)

There is no right or wrong way to do any of this. Finding the best solution is what this is all about.

Here is the Markel catalog I use at work. Page 80 has floor registers with heating coils in them. You may need a few of them. They also have a huge assortment of other styles of electric heaters you can look at. 
http://www.tpicorp.com/QR/markel-H.pdf

You can always look at these:
Home Smoke Eater Product Reviews: Residential and Room Home Smoke Eaters Comparisons Chart

I can't say from personal experience how well they work, but idea is to filter the air instead of exhausting it. Don't pay too much attention to the HEPA filters they advertise. They only get that rating because when they test and rate them by standard they work like HEPA filters, but after a little use they are no where near as good. HEPA filters are used in medical facilities because the particle size they trap is microscopic.


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